Valve mechanism for rock-drills.



PATEN'I'BD SEPT. 8, 1903. T. OFFICER.

VALVE MECHANISM FOR ROCK DRILLS.

APPLICATION FILED JAN. 29. 1902.

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NUHRYS PETERS co. womumov w No. 738,229. P'ATENTED SEPT. a, 1903.

T. OFFICER. VALVE MECHANISM FOR ROGKDRILLS.

APPLIUATION FILED JAN. 29. 1902.

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UNITED STATES Patented September 8, 190%.

PATENT OFFICE.

THOMAS OFFICER, OF OLAREMONT, NEW HAMPSHIRE, ASSIGNOR TO SULLIVANMACHINERY COMPANY, OF OLAREMONT, NEW HAMP SlIlRE, A CORPORATION OF NEWVHAMPSHIRE.

VALVE MECHANISM FOR ROCK-DRILLS.

SPECIFICATION forming part of Letters Patent No. 738,229, datedSeptember 8, 1903.

Application filed January 29, 1902- Serial No. 91,726. (No modelJ To allwhom it may concern.-

Be it known that I, THOMAS OFFICER, a citizen of the United States,residing at Claremont, in the county of Sullivan and State of NewHampshire, have invented an Improvement in Valve Mechanism forRock-Drills and the Like, of which the following description, inconnection with the accompanying drawings, is a specification, likeletters on the drawings representing like parts.

My invention relates to pressure-actuated valve mechanismssuch, forinstance, as are commonly used in rock-drills, rock-channelers,coal-cutters, and the likethe object of my invention being to simplifyand cheapen the mechanical construction and at the same time improve theoperation thereof.

My invention aims, among other things, to provide novel and improvedmeans for pressure-locking or holding the valve in position during thetravel of the usual piston or during such portion of such travel as itis desired said valve shall remain in fixed position. Difficulty hasheretofore been experienced in maintaining the certainty of valvemovement and position after the parts become worn so as to producevarious leakages. My invention aims to avoid this difficulty byproviding means for disposing of such leaking pressure as would if notdisposed of interfere with the operation and positioning of the valve.

The foregoing with other features of my invention will be hereinafterfully disclosed in connection with the accompanying drawings,illustrating one embodiment of myinvention.

In the accompanying drawings, Figure 1 is a longitudinal section of arock-drill equipped with a valve mechanism, illustrating one embodimentof my invention, the piston, its rod, and the valve being in elevation;Fig. 2, a similar view with the piston and valve in different positions;Fig. 3, a vertical cross-section on the dotted line 3 3, Fig. 1; Fig. 4,a vertical cross-section on the dotted line 4: 4, Fig. 1; Fig. 5, a topor plan view of Fig. 1 with the valve'chest removed to show the locationor formation of the cylinder-ports; Fig. 6, an under side view of thevalve-chest;

the use of air.

Fig. 7, a detail showing the valve detached, and Fig. 8 a sectionaldetail illustrating a modified construction.

In the embodiment of my invention selected for illustration herein andshown in the drawings, A is a usual pressure-cylinder containing apiston 13, the piston-rod b of which is fitted at its end with a usualchuck b, in which may be clamped the drill or cuttingtools. (Not shown.)At the top or back end of the cylinder is provided a usual ratchetmechanism b controlling a usual rifle-grooved spindle N, which producesstep-by-step rotation of the piston and its tool or tools as the sameare reciprocated. At one side of the cylinder A is attached avalve-chest O, conas a piston -valve. This valve, as shown, comprisesthree connected pistons d d 61 shown as of equal diameter and arrangedto slide axially in a valve seat or chamber that may be formed by boringstraight through a suitable casting of which the valve-chest may becomposed. The ends of this chamber are closed by screw-plugs o c. In thereciprocations of the valve the middle piston d shifts from one to theother side of the inlet-port c, placing the latter alternately incommunication with the cylinder-ports c 0 arranged at either sidethereof and leading, respectively, to opposite ends of the cylinder toadmit fiuid under pressure thereat for moving the plunger therein in oneor the other direc tion, according to the particular end of the cylinderat which the pressure is admitted. While my invention is equally adaptedfor use in connection with steam, air, or any other fluid underpressure, I shall for convenience hereinafter refer to such fluid asair, but Without thereby restricting my invention to The endvalve-pistons d d control, respectively, the exhaust-ports 0 0 arrangedadjacent thereto and outside of and beyond the cylinder-ports o creferred to. These exhaust-ports both communicate with a common exhaustoutlet 0. The screwplugs c c are provided, respectively, with stopprojections c to limit the movements of the valve in both directions.

taining a pressure-actuated valve D, shown Assuming the parts to be inthe positions Fig. 1, air under pressure admitted through the sideinlet-port 0 will enter the cylinderport 0 at the right, Fig. 1, andpass to the back or top end of the cylinder, where it will act upon andmove the cylinder-piston B to the left to the opposite end of thecylinder, the exhaust from the opposite side of the cylinder-pistonescaping through the exhaustport 0 The chambers c c at the extreme endsof the valve-chamber, between the exhaust-pistons d d and the adjacentplugs c 0- which chambers, for convenience only, I callcirculationchambersare provided, respectively, with reversing-ports e e,which extend in opposite directions, crossing each other, as shown, andentering the cylinder each near an end thereof which is opposite the endadjacent which it started, and the exhaust-pistons d d (see Fig. 7) areperforated, respectively, with small locking ports or passages 6 6leading from one to the op posite side thereof.

When the valve was moved into its position Fig. 1 to admit air from theinlet -port 0 through the cylinder-port c to move the cylinder-piston,as described, air also was admitted, through the small locking-port e inthe valve exhaust-piston d, into the circulation-chamber 0 between saidpiston and its adjacent plug 0, thence out from said chamber through thereversing-port 6 into the exhaust end of the cylinder, from which itescapes with the exhaust-air therefrom, as described. Thus during thetime the valve is in its position Fig. 1 there is maintained a constantcirculation of air through the chamber c at the end d of the valve, andnotwithstanding the reversing-port e is larger in area than the smallpiston locking-port c there is retained a reduced but nevertheless asuflicient pressure in the said chamber, acting upon the end face of thesaid valve-piston, to hold the latter and the valve lockednnder pressureor pressure-locked in the position into which it was moved.

When the cylinder-piston has moved along in its cylinder a givendistance to the left, Fig. 1, determined by the nature of the work andthe blow to be delivered, said piston passes and uncovers the cylinderend of the reversingport e, permitting air from the cylinder to entersaid port, passing therethrough to the circulating-chamber c in front ofthe exhaustpiston 61 of the valve, circulating through said chamber, andescaping therefrom through the small piston-port 6 into and out throughthe eXhaust-portc ;butthepiston-porte issmaller than the reversing-porte. Consequently the circulating air becomes choked in said chamber,being unable to escape therefrom as rapidly as it enters, thus creatinga pressure therein which exceeds the reduced pressure of the aircirculating through the chamber c at the opposite end of the valve. Thisexcess of pressure of the choked air at the the exhaust-port c and themiddle piston 61' to move to the opposite side of the inlet-port c topermit air from the latter now to pass to the left of said piston, toand through the cylinder-port 0 to the left-hand end of the cylinder, toreturn the cylinder-piston in the opposite direction from its formermovement described. This reverse movement of the valve also moves itsexhaust-piston d to the right and uncovers its eXhaust-port c to permitthe air to exhaust from the right-hand end of the cylinder through theport 0 exhaust-port c, and exhaust-outlet 0 The valve remains in thisposition, Fig. 2, locked by the air circulating through the chamber andreversing-port 8 leading therefrom until the piston in its returnmovement to the right passes and uncovers the cylinder end of the saidreversing-port e, permitting air to enter from the cylinder and passthrough to the circulating-chamber c at the right of the valvepiston,and being unable to escape freely therefrom through the smallerpiston-port 6 will choke in said chamber and create thereby an excess ofpressure over the reduced pressure of the circulating air in the cham- 1ber c at the opposite end of the valve, which will move the valve backagain to the left into its original position, Fig. 1. This will causethe valve-piston d to cover its exhaustport 0 and will move thevalve-piston d to the left of the inlet-port c, admitting pressuretherefrom to the cylinder-port c and will uncover the exhaust-port c atthe opposite end of the cylinder. The air admitted from the inlet-portto the cylinder-port 0 also passes through the small piston-port e tothe circulating-chamber c at the righthand end of the valve, circulatingthence through the reversing-port e to the exhaust and maintainingsuii'icient though reduced pressure in said chamber to lock said valvein position. The valve is thus pressure-locked ineach of its positionsby live air taken direct from the inlet 0 and caused to flow orcirculate through one orthe other of the chambers c or c", the valvebeing so held or locked until the cylinder-piston in its travel passesand uncovers one of the reversing-ports e or 6, when the admission ofair therethrough from the cylinder creates excess of pressure in onecirculating-chamber over the other to shift the valve. This pressure formoving the valve is, however, relatively slowin accumulating, becausethe piston-ports e 6 provide an escape for the air almost as fast as itenters. Hence the valve is relatively slow in responding. This is ofadvantage, for it renders it possible to place the cylinder ends of thereversingports at a considerable distance from the ends of the cylinderto render possible short strokes ofthe piston when required; yet whenthe piston is moving rapidly throughout its full stroke it givesopportunity for the piston after uncovering the reversing-port tocomplete its stroke before the valve responds and changes its positionto reverse the stroke.

It will be noticed that at or about the time the rear end of thecylinder-piston inits movement passes and uncovers the reversingport atone end of the cylinder the other or leading end of the piston reachesand covers the reversing-port at the other end of the cylinder, and ifno other outlet from such port were provided the circulation of airthrough the circulation -chamber holding the valve locked would stop andthe pressure therein would accumulate to such a degree that the airadmitted to the corresponding chamber at the opposite end of the valvethrough the uncovered reversing-port would be insufficient to move thevalve. I have provided for this, however, by longitudinallyorcountergrooving the piston between its ends, as at b and the circulating airwhen prevented from escaping with the other exhaust from in front of theadvancing piston may enter these longitudinal grooves b in the pistonand escape therefrom through the circumferential port a, formed in theinner Wall of the cylinder and communicating by divergent passages a,Figs. 1 and 5, with the exhaust ports a c referred to. Thus there isprovided substantially at all times the required vent for the chambercontaining the reduced holding pressure to enable the valve to be movedby greater pressure at the other end of the valve.

Upon wear of the parts should any live air from behind the piston leakalong the side thereof and prematurely enter the still coveredreversing-port said leaking air would fail to shift the valve, becauseeither small port 6 e in the exhaust-piston and vent-port a aresufficient to take care of any amount of air that could leak past thepiston, permitting such air to escape into the exhaust-port.

In lieu of the small ports 6 e in thevalvepistons 01 d for venting thecirculation-chambers at the exhaust end of the valve and for admittinglive air to such chamber at the holding or looking end thereof I mayemploy ports or passages e c, Fig. 8, formed in the wall of thevalve-chamber and extending around the valve-pistons cl 61 the operationremaining the same. The valve remains locked until the cylinder-pistonin its travel passes and uncovers the reversing-port, and should thesaid piston fail to move through a sufficient portion of its stroke touncover such port then the valve will remain locked until the piston hasbeen freed or the machine moved so as to permit the piston to movesufficiently to uncover the reversingport. There is therefore noliability that resistance to the drill, as by clogging or otherwise,will prematurely shift the valve and cause unduly short strokes.

My invention obviously is not restricted to the particular embodimentthereofhere shown and described, as the same may be varied Withoutdeparting from the spirit and scope of my invention.

I claim 1. A valve mechanism containing a pressure-actuated valve, achamber for each end thereof, means to admit actuating pressure to saidchambers from the cylinder to reverse said valve, means to admit lockingpressure also to said chambers from a source independent of saidcylinder, and means to vent both said chambers with the valve in each ofits extreme positions.

2. A cylinder valve mechanism containing a pressure-actuated,pressure-locked valve, means to supply locking pressure thereto andmeans to maintain an exhausted and vented chamber opposed to andthroughout the operation of the actuating pressure.

3. A cylinder valve mechanism containing a valve, and means to lock thesame by the agency of circulating fluid under pressure from a sourceindependent of said cylinder and acting at the end of said valve.

4:. A cylinder valve mechanism containing a pressure-actuated valvehaving an admission-controlling piston and exhaust-controlling pistonsat opposite sides thereof, and means to lock said valve in positionthrough the agency of circulating fluid under pressure from a sourceindependent of the cylinder and admitted to act upon one or another ofsaid exhaust-controllingpistons.

5. A cylinder valve mechanism containing a valve, means to lock the samethrough the agency of circulating fluid under pressure from a sourceindependent of said cylinder, and means to maintain an exhausted andvented chamber opposed to said locking fluid.

6. A valve mechanism containing a pressure-actuated valve and means tomove the same through the agency of an excess of pressure of circulatingfluid at one end of said valve over the pressure of circulating fluid atthe opposite end of said valve.

7. A valve mechanism containing a pressure-actuated valve with means toadmit live fluid under pressure thereto from the cylinder from behindthe moving piston therein to move said valve and means to admit fluidunder pressure thereto from a source independent of said cylinder tolock said valve in position when moved.

8. A valve mechanism containing a pressure-actuated valve with means toadmit circulatinglive fluid under pressure thereto from the cylinderfrom behind the moving piston therein to move said valve and means toadmit circulating fluid under pressure thereto from a source independentof said cylinder to lock said valve in position when moved.

9. A valve mechanism containing a valve and its chamber with inlet andoutlet ports of different area at each end of said valve, said valvebeing moved by fluid under pressure admitted through the larger of saidend ports and locked by fluid under pressure admitted through thesmaller of said end ports.

10. A cylinder valve mechanism containing a valve-chamber and its valveprovided with end pistons, ports communicating with the chambers atopposite sides respectively of said pistons, and a third piston betweensaid end pistons and controlling admission of live fluid under pressureindependently of the cylinder to said ports.

11. A cylinder valve mechanism comprising a cylinder and piston, avalve-chamber and Valve, the latter provided with end pistons, lockingand actuating chambers for said pistons communicating with a'source oflive ree-$29 Witnesses:

F. H. FOSTER, J. S. UPHAM.

